Nature Nanotechnol. doi: 10.1038/nnano.2009.333 (2009)

Cancer can become more deadly when tumour cells spread from one tissue type to another. A technique that uses two kinds of nanoparticle could help to trap and detect these rare cells in the bloodstream, potentially enabling earlier cancer diagnosis, according to Vladimir Zharov of the University of Arkansas for Medical Sciences in Little Rock and his colleagues.

The researchers first inoculated the flank areas of mice with human breast-cancer cells to create tumours, followed later by an injected mixture of magnetic iron nanoparticles and gold-plated carbon nanotubes, each of which could bind to different cancer-cell receptors. The team then applied a magnet to the mouse ear to capture the particle-bound tumour cells, and pulsed the particles with a laser that triggered a photoacoustic signal. The technique detected a rising number of tumour cells in the blood vessels as the primary tumour developed throughout the four-week experiment.